This invention relates to the design of suppression devices for controlling the electro-magnetic radiation which is radiated from electronic devices such as computer processors and, more specifically, to the testing of design parameters of such devices by providing readily changeable structural parameters of such an electro-magnetic radiation suppression device.
United States government standards require control of electro-magnetic interference for all devices such as computers, servers, and other electronic devices which may emit electro-magnetic radiation from their electronic components. Electro-magnetic interference is defined as the adverse affects of electro-magnetic radiation emitted in proximity to an electro-magnetic radiation sensitive device.
Electro-magnetic interference can be caused by electro-magnetic radiation which has escaped from a device within which it is generated. Electro-magnetic interference can cause interference with the proper operation of television sets, radios and other electronic devices; moreover, it can interfere with computers and servers wherein the foreign electro-magnetic interference affects the reliability and/or performance of computer processors in such systems.
Whenever electro-magnetic radiation suppression enclosures are sealed in an effort to contain or suppress the escape of electro-magnetic radiation from the region in which it is generated, these efforts are usually quite effective. The enclosures need only to totally enclose the electro-magnetic radiation generating source and to be electrically grounded. However, it is seldom practical to perfectly enclose the electro-magnetic radiation source inasmuch as the electro-magnetic radiation sources are commonly mounted on circuit boards which may not be practically enclosed totally. Additionally, the electro-magnetic radiation source may generate sufficient heat during its operation that the heat must be dissipated in order to prevent the electronic devices from overheating and resulting in circuit or component failure.
The least expensive cooling technique is the passage of cooling air through the electro-magnetic radiation suppression shield. This approach requires air flow openings in the electro-magnetic radiation suppression shield. The cooling air flow openings in the electro-magnetic radiation suppression enclosures or shields also provide escape routes for the electro-magnetic radiation. As it becomes impossible to totally eliminate the escape of electro-magnetic radiation and to simultaneously air cool the computer processors or other sources of electro-magnetic radiation, an acceptable compromise may be obtained with the reduction of the size of the holes in the air flow path, which reduces the escape of electro-magnetic radiation and the wavelengths of any escaping electro-magnetic radiation. If the holes are formed into or by an electrically conductive material such as sheet metal or electrically conductive screening, the large plurality of holes of relatively small dimensions will reduce very significantly the electro-magnetic radiation passing through the air flow aperture in the electro-magnetic radiation shield or suppression enclosure.
The electrically conductive electro-magnetic radiation suppression plate placed in an air cooling opening in the electro-magnetic radiation suppression shield greatly reduces the escaping electro-magnetic radiation and reduces its effect on the remaining escaping electro-magnetic radiation which then becomes a lower level electro-magnetic interference.
To a great extent, the control of electro-magnetic radiation and the reduction of the electro-magnetic interference with other electronic equipment is accomplished by xe2x80x9ctrial and errorxe2x80x9d design. The enclosures are fabricated and tested and, from these results, variations of the enclosure are fabricated and tested. This process can be and is repeated many times at a substantial expense before determination of an acceptable level of electro-magnetic interference and the specific design of the electro-magnetic radiation suppression enclosure.
The design and verification process to suppress and control electro-magnetic radiation can be laborious and time consuming as well as expensive. Continuing goals of electro-magnetic radiation control and suppression designers are to shorten, improve, and reduce the cost of electro-magnetic radiation suppression enclosure design as well as to improve the air flow characteristics of cooling designs thus incorporated into the electro-magnetic radiation suppression devices.
It is an object of the invention to improve the design of electro-magnetic radiation suppression shields, thereby improving control of electro-magnetic interference.
It is another object of the invention to assist in the design of improved electro-magnetic radiation suppression enclosures for use in devices having electro-magnetic radiation generating electronic components.
It is a further object of the invention to eliminate the need to fabricate a large plurality of test specimens of electro-magnetic radiation suppression enclosures, each incorporating some of the variations of test parameters for testing the electro-magnetic radiation escape from the enclosures.
It is an additional object of the invention to provide a degree of variability in a plurality of parameters that may effect the level of electro-magnetic interference outside the electro-magnetic radiation suppression enclosure being designed.
It is still an additional object of the invention to provide for a variation of the type of electro-magnetic radiation suppression plate being tested while providing both ease in changeability and adequate cooling air flow.
It is a still further object of the invention to provide for variable placement of test electro-magnetic radiation suppression plates relative to the cooling air flow openings in each electro-magnetic radiation suppression enclosure being tested.
Other objects of the invention will become apparent to one of ordinary skill in the art.
The shortcomings of the prior art are overcome and the objects of the invention accomplished by the present invention summarized below.
A hollow metal container or enclosure, an electro-magnetic radiation suppression shield, is provided with a back or rear wall which is removable and which has an electro-magnetic radiation source support mounted thereon. The electro-magnetic radiation source support is capable of extension and retraction to permit variable positioning of the electro-magnetic radiation source within the metal container for ease in the electro-magnetic radiation testing. The electro-magnetic radiation suppression shield is provided with an end plate which also is easily removable. A removable end plate supports electro-magnetic radiation suppression plates and further is provided with electro-magnetic radiation suppression plate mounting hardware to dispose at various separations the electro-magnetic radiation suppression plates. The hardware also permits easy changing of the separations between the electro-magnetic radiation suppression plates. The electro-magnetic radiation suppression plates may be interchanged to allow testing of various air flow hole sizes, shapes, and patterns. Similarly, if desired, the size and pattern of the air passages or openings in the end wall or end plate may be varied to provide variations in air flow capacity.
The provision to enable easy changes in the configuration of test apparatus allows testing of a large number of design configurations of electro-magnetic radiation suppression plates, the spacing of the electro-magnetic radiation suppression plates, and positioning of the electro-magnetic radiation suppression plates relative to an electro-magnetic radiation source.
The use of this invention results in an effective improvement in electro-magnetic radiation suppression for products because the invention simplifies testing a large number of parameters and thus the selection of design parameters which result in the lowest electro-magnetic radiation escaping from the electro-magnetic radiation shield design in the final product.
A more complete understanding of the invention may be had from the attached drawings and the detailed description of the preferred embodiment of the best mode of the invention which follows.